Perrygraf Payne Residential Heating & Cooling Load Calculator

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Country of manufacture: U.S.,            Date of manufacture: ca. 1957
Diameter: 20.4 cm,      Weight: 51.3 gms
Materials: cardboard; wraparound cursor is plastic.
Scales: numerous, specialty
Front
     Outer Disk:
     Inner Disk:
Back
     Outer Disk:
     Inner Disk:
Condition: C5 (Normal Signs of Use
Came with: Cardboard sleeve imprinted with instructions
Note: I do not know that this thing was actually produced by Perrygraf. It is identical in style, construction, and font to other Perrygraf items but but there is no indication of who actually produced it anywhere on the device. Any ideas?

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